以下是引用jessica_yuan在2008-3-26 0:21:00的发言：求牛牛解答以下的GWD数学题，本人百思不得其解~~~~~~十万分感谢！！！！！！！！！！！
每题后的答案为正确答案，谢谢！！
GWD 01
Q10:
A set of numbers has the property that for any number t in the set, t + 2 is in the set. If –1 is in the set, which of the following must also be in the set?
I. -3
II. 1
III. 5
A. I only
B. II only
C. I and II only
D. II and III only
E. I, II, and III
Answer: D
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为什么-3不在set 中，而5在set中？你自己仅用题目所给的条件尝试推导出-3来看看？然后我再根据你的推理指出其中破绽。
Q28:
For any positive integer n, the sum of the first n positive integers equals [n(n+1)]/2. What is the sum of all the even integers between 99 and 301?
A. 10,100
B. 20,200
C. 22,650
D. 40,200
E. 45,150
Answer: B
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“sum of all the even integers between 99 and 301”=2*(sum of all integers from 50 to 150)，自己算吧。
Q30:
Joanna bought only $0.15 stamps and $0.29 stamps. How many $0.15 stamps did she buy?
(1) She bought $4.40 worth of stamps.
(2) She bought an equal number of $0.15 stamps and $0.29 stamps.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: D
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我觉得但是B条件不可以，因为只要数量相等，随便买多少都可以~~~~~~
我觉得但是B条件不可以，因为只要数量相等，随便买多少都可以~~~~~~
GWD 02
Q8:
The operation Ä is defined for all nonzero numbers a and b by a Ä b = a/b – b/a. If x and y are nonzero numbers, which of the following statements must be true?
I. x Ä xy = x(1 Ä y)
II. x Ä y = -(y Ä x)
III. 1/x Ä 1/y = y Ä x
A. I only
B. II only
C. III only
D. I and II
E. II and III
Answer: E
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我觉得 I,II,III都可以啊~~~~~~~~·I的左边是(1/y-y)，右边是x*(1/y-y)，除非x=1，否则怎么会“must be true”
我觉得 I,II,III都可以啊~~~~~~~~·I的左边是(1/y-y)，右边是x*(1/y-y)，除非x=1，否则怎么会“must be true”
GWD 03
GWD 03
Q14:
How many seconds will it take for a car that is traveling at a constant rate of 45 miles per hour to travel a distance of 22 yards? (1 mile = 1,160 yards)
A. 8
B. 9
C. 10
D. 11
E. 12
Answer: C
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这题貌似简单，但不知道为什么我算了好多遍得出结果都是1.5秒左右~~~~~
我的算法：22/(45*1160/3600)根据你所列出的题目，你的算法没错。要么题目数据有问题，要么题目要求抄得不对。实际上1mile = 1760 yards，另外题目可能是问220yards而非22yards
Q18:
Last year the price per share of Stock X increased by k percent and the earnings per share of Stock X increased by m percent, where k is greater than m. By what percent did the ratio of price per share to earnings per share increase, in terms of k and m?
A. k/m %
B. (k-m) %
C. [100(k-m)]/(100+k) %
D. [100(k-m)]/(100+m) %
E. [100(k-m)]/(100+k+m) %
Answer: D
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GWD 06
GWD 06Q6:
If a, b, k, and m are positive integers, is ak
a factor of bm?
(1) a is a factor of b.
(2) k ≤ m
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: C
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Q26:
K is a set of integers such that if the integer r is in K, then r + 1 is also in K. Is 100 in K?
(1) 50 is in K.
(2) 150 is in K.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: A
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GWD 08
GWD 08
Q9:
If an integer n is to be chosen at random from the integers 1 to 96, inclusive, what is the probability that n(n + 1)(n + 2) will be divisible by 8?
A. 1/4
B. 3/8
C. 1/2
D. 5/8
E. 3/4
Answer: D
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对于所有偶数，n(n + 1)(n + 2)一定是8的倍数；奇数中除8余7的所有数字都能保证n(n + 1)(n + 2)能被8整除，这种数字每4个奇数中存在一个。这样一来共有1/2+1/4*1/2的数字符合要求。
GWD 09
Q10:
What is the value of (x - y)4?
(1) The product of x and y is 7.
(2) x and y are integers.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: C
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The product of x and y is 7.意思是x*y=7。连同x,y都是整数的条件可得(1,7),(7,1),(-1,-7),(-7,-1)这4组(x,y)。无论哪一组，(x-y)的4次方都是1296
Q20:
| Favorable | Unfavorable | Not Sure |
Candidate M | 40 | 20 | 40 |
Candidate N | 30 | 35 | 35 |
The table above shows the results of a survey of 100 voters each responded “favorable” or “unfavorable” or “not sure” when asked about their impressions of candidate M and of candidate N. What was the number of voters who responded “favorable” for both candidates?
(1) The number of voters who did not respond “favorable” for either candidate was 40.
(2) The number of voters who responded “unfavorable” for both candidates was 10.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: A
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GWD 10
Q8:
An equilateral triangle that has an area of 9 √3 is inscribed in a circle. What is the area of the circle?
A. 6派
B.9派
C.12派
D. 9派 √3
E. 18派√3
Answer: C
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你试试看用圆半径r来表示内接正三角形的面积。
GWD 11
GWD 11Q7:
Before a certain tire is used, 40 percent of its total weight consists of tread. If during a lifetime of use, 50 percent, by weight, of the tire’s tread is lost and no other parts of the tire is lost, what per cent of the tire’s total remaining weight consists of the remaining tread?
A. 55%
B. 20%
C. 25%
D. 30%
E. 35%
Answer: C
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我解到是20%~~~~~~~~~~
Q21:
A certain circle in the xy-plane has its center at the origin. If P is a point on the circle, what is the sum of the squares of the coordinates of P?
(1) The radius of the circle is 4.
(2) The sum of the coordinates of P is 0.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: A
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题目有点多，真的十分十分感谢！！！！！！！！！！！！！！！
题目有点多，真的十分十分感谢！！！！！！！！！！！！！！！
问题好多，先随便解答几个。
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发表于 2008-3-26 00:21:00
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